1. Field
The present invention relates to a phosphor and a light emitting device.
2. Description of Related Art
A phosphor is excited by light with a particular wavelength and emits light with a wavelength different from the particular wavelength. Such a phosphor is widely used together with a light emitting diode (LED).
Conventional phosphors have some problems. First, the conventional phosphors have weak emission intensity in a visible light region (including a blue wavelength). Secondly, a wavelength of the emitted light does not match an ideal peak wavelength. Thirdly, the emission intensity is reduced with temperature increase. For example, as a temperature rises, luminance of the phosphor is reduced (Thermal Quenching).
Meanwhile, a variety of conventional phosphors include an oxide based fluorescent material using rare earth elements. The oxide based fluorescent materials has been already widely known and some of the oxide based fluorescent materials are now being actually used. However, unlike the oxide based fluorescent material used in CCFL for PDP, CRT and LCD, an oxide based fluorescent material for LED is required to efficiently emit light by ultraviolet rays and light having a blue wavelength.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.